What Is Parabolan? Half-Life, Dosing Math & How to Track It
Also known as: Trenbolone Hexahydrobenzylcarbonate · Tren Hex · Parabolan
Parabolan is the historical trade name for trenbolone hexahydrobenzylcarbonate, trenbolone attached to one of the longer esters used with it — a chain with a half-life of roughly 8 days, versus the acetate ester’s 1–3 days, and historically dosed roughly every 10 days. About 66% of the milligrams in the vial are trenbolone itself. It carries the same non-aromatizing, progesterone- and glucocorticoid-receptor-active risk profile as any trenbolone ester, just on a slower clock. Educational only; not a recommendation to use.
What Parabolan is and how it works
Parabolan was originally a French pharmaceutical product (Negma Laboratories), discontinued in the 1990s, that paired trenbolone with the hexahydrobenzylcarbonate ester — a long, bulky carbon chain that creates one of the slower-releasing depots of any trenbolone ester in common use, with a half-life of roughly 8 days, historically dosed about once every 10 days.
The base hormone is identical to trenbolone acetate or enanthate: it binds the androgen receptor strongly, does not meaningfully aromatize to estrogen, and — unlike testosterone or nandrolone — engages the glucocorticoid receptor in addition to the progesterone receptor, which is one hypothesized contributor to trenbolone’s more distinctive reported effects on sleep and mood, though the mechanism isn’t firmly established and is likely multifactorial.
What changes with the hexahydrobenzylcarbonate ester is only timing: about 66% of the milligrams in Parabolan are trenbolone itself, with the rest being the ester weight that buys the long release profile.
Dosing math & the mg/mL trap
Parabolan is labeled by concentration like any injectable ester: volume (mL) = dose (mg) ÷ concentration (mg/mL). Because the ester is long and per-injection amounts tend to be larger given the less-frequent schedule, a concentration mix-up translates into a larger absolute volume error than it would with a short-ester compound.
If splitting a weekly total across two injections, divide by two before applying the volume formula — the same one-line math, just applied to a smaller per-shot amount.
| Amount | 75 mg/mL | 100 mg/mL | 150 mg/mL |
|---|---|---|---|
| 50 mg | 0.67 mL (67u) | 0.50 mL (50u) | 0.33 mL (33u) |
| 75 mg | 1.00 mL (100u) | 0.75 mL (75u) | 0.50 mL (50u) |
| 100 mg | 1.33 mL (133u) | 1.00 mL (100u) | 0.67 mL (67u) |
Volume to draw at three reference concentrations (U-100 syringe units in parentheses). Reference numbers for the arithmetic only — the HRT tab of the calculator handles any concentration.
Half-life & what it means for frequency
At roughly 8 days, the hexahydrobenzylcarbonate ester supports a schedule of about once every 10 days (how it was historically dosed) to weekly — longer than the every-other-day schedule trenbolone acetate needs, but shorter than the longest esters like boldenone undecylenate (~14 days) — and it still takes several weeks of consistent injections before blood levels stop climbing.
That same length means a long tail after the last injection: any side effects that show up — mood, sleep, lipids, blood pressure — resolve on a timeline of weeks to months rather than days, the trade-off for fewer injections along the way.
What to monitor & the real risks
The risk profile is identical to any other trenbolone ester because the hormone is the same: blood pressure and a lipid panel (trenbolone is a notable HDL suppressor) deserve regular attention, alongside standard hematocrit monitoring for any injectable AAS.
Renal markers (creatinine, eGFR, urinalysis) and prolactin (from progestogenic activity) round out a reasonable panel, along with total/free testosterone and LH/FSH for HPTA suppression — estradiol only matters if other aromatizing compounds are part of the protocol, since trenbolone itself doesn’t convert to estrogen. Sleep, night sweats, and mood are worth tracking as symptoms; with an 8-day ester, any shift in these builds and resolves more gradually than with the acetate version.
How to track Parabolan in Stackeddd
Log every Parabolan injection with its dose and site, and keep blood pressure, lipids, renal markers, and mood/sleep notes trending alongside it — with an 8-day ester, the pattern only becomes visible over several weeks of consistent logging.
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Dosing Calculator (HRT tab)
Model it yourself: enter your dose and vial concentration on the HRT tab and get the exact mL and syringe units for any amount — the same math built into the Stackeddd app.
Related compounds
Related reading: TRT Math: what mg/mL actually means · Injection frequency: daily vs EOD vs weekly
Frequently asked questions
What is Parabolan’s generic name?
Trenbolone hexahydrobenzylcarbonate — Parabolan was the trade name for a French pharmaceutical product (Negma), discontinued in the 1990s, that paired trenbolone with one of its longest common esters.
What is the half-life of Parabolan?
Roughly 8 days for the hexahydrobenzylcarbonate ester, historically dosed about once every 10 days — longer than the every-other-day schedule trenbolone acetate needs, though shorter than the longest esters like boldenone undecylenate (~14 days).
How do you calculate a Parabolan dose in mL?
Volume (mL) = dose (mg) ÷ concentration (mg/mL). A 75 mg amount from a 75 mg/mL vial is 1.00 mL, or 100 units on a U-100 syringe. The HRT tab of the calculator handles any concentration.
What should you monitor on Parabolan?
The same panel as any trenbolone ester: blood pressure, a lipid panel, hematocrit, renal markers, and prolactin. Sleep, mood, and night sweats are worth logging too — with an 8-day ester, changes build and resolve more slowly than with trenbolone acetate.
This is educational information, not medical advice. Doses and protocols above reflect published references and community practice — protocol decisions belong with your prescribing physician. Generic names used throughout. How this reference is built & how the AI is tested →
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